(2√5+3)(2√5+3)= a + b√c+d

Figure out the binomial to find a,b,c,d

just expand like normal binomial multiplication: (a+b)^2

(2√5+3)(2√5+3)
= (2√5)^2 + 2(2√5)(3) + 3^2
= 4*5 + 12√5 + 9
= 20 + 12√5 + 9